Direct Methanol Fuel Cell Anode Research Articles

Nanoarchitectonics for modulation on the electronic structure of ultrafine PtRuFe nanowires as robust methanol electrooxidation catalysts

The widespread adoption of Pt-based electrocatalysts in the anode side of direct methanol fuel cell (DMFC) faces challenges stemming from their limited activity, stability, and high cost. Herein, ultrafine PtRuxFey trimetallic nanowires (PtRuxFey NWs) with a diameter of approximately 1.25 nm were synthesized for the electrocatalytic methanol oxidation reaction (MOR). The structure-activity relationship between the electronic structure of PtRuxFey NWs and their electrocatalytic performance was established by meticulously controlling the addition of Ru(acac)3 and Fe(Ac)2. Under optimal conditions, PtRu0.25Fe0.14 NWs displayed remarkable MOR performance, boasting the mass activity (1332.3 mA mgPt−1) and specific activity (1.0 mA cm−2), a 4.0-fold and 1.8-fold enhancement over that of the commercial catalysts. Additionally, after a chronoamperometry test, PtRu0.25Fe0.14 NWs demonstrated a current density 8.3 times higher than that of Pt/C under the same test conditions. The excellent MOR performance of PtRuxFey NWs can be attributed to their one-dimensional and ultrafine structure advantages, the electronic effects of Ru/Fe on Pt, and the bifunctional capabilities. Our research may lead to a simple and controllable strategy that combines various approaches to enhance the performance of Pt-based electrocatalysts in the anode of DMFC.

Construction of Ternary PtRuPd Alloy Supported on Carbon Nanotubes for Concentrated Methanol Oxidation

AbstractDue to the complex reaction process involving six‐electron transfer, high overpotential and slow kinetic rate of methanol oxidation, the development process of direct methanol fuel cells (DMFC) has been hampered. Herein, a simple one‐step solvent reduction approach was employed to simultaneously reduce metal ions supported on carbon nanotubes and prepared ternary metal alloy nanoparticles supported on carbon nanotubes electrocatalyst (PtRuPd@CNT). Compared with PtRu@CNT binary metal catalyst, the as‐prepared PtRuPd@CNT ternary metal catalyst displayed more outstanding methanol oxidation reaction (MOR) catalytic performance and good CO anti‐poisoning ability. In the case of using 8 M methanol, the MOR performance of PtRuPd@CNT was 1.8 times better than the PtRu@CNT electrocatalyst. The addition of the Pd atom regulates the surface electronic structure of PtRu alloy, and the strong electronic interaction enhances the MOR activity of the PtRu@CNT catalyst. Furthermore, the addition of the Pd atom in the PtRuPd@CNT electrocatalyst also diminishes adsorption of CO intermediate species on the Pt surface, boosting the CO anti‐poisoning ability of the catalyst and improving the stability. Therefore, the PtRuPd@CNT electrocatalyst incorporating the Pd atoms could actualize the practical application prospect as an efficient concentrated DMFC anode catalyst.

Palladium supported on NiFe layered double hydroxide as an effective electrocatalyst for methanol electro-oxidation

Pt and Pd have an excellent catalytic capacity for methanol oxidation and have the highest discharge efficiency among direct methanol fuel cell anode materials. However, the catalyst produces carbon monoxide and other intermediates (*COad) during the methanol oxidation process, causing Pt/Pd active site poisoning. In this work, Pd was introduced into the layered double hydroxide (NiFe-LDH) by hydrothermal method, and CO-poisoning was successfully inhibited. NiFe-LDH has a larger Pd-loaded surface and provides a more efficient platform for the formation of *OH, which can effectively promote the oxidation of *COad (2 *OHad+*COad→CO2 +H2O) and improve the activity of Pd. The Pd/Ni4Fe6-LDH shows excellent OER activity (overpotential is 268 mV @ 20 mA cm−2) and MOR activity (mass activity is 2665.3 mA mg−1Pd). The Ni4Fe6-LDH synergetic Pd opens the door for reducing the CO-poison and enhancing the MOR durability for the long-use life of DMFCs.

Construction of gradient catalyst layer anode by incorporating covalent organic framework to improve performance of direct methanol fuel cells

Improving cell performance is the most demanded task in direct methanol fuel cell (DMFC) research, although this fuel cell has several intrinsic features like high energy density, moderate operating temperature and environmentally friendly operation. The catalyst layer (CL) is the site of electrochemical reactions directly affecting the cell performance. Accordingly, the structure and preparation of the CL are crucial in optimizing performance. In this study, a novel gradient catalyst layer (G-CL) for the anode of DMFC is developed and better performance is obtained compared with that of single catalyst layer (S-CL) anode. A G-CL anode is composed of an outer CL of covalent organic framework (COF) materials-mixed catalyst near the microporous layer (MPL) and a conventional inner CL near the membrane side. Different loading of Pt catalyst in the two layers. Therefore, in the G-CL structure, there existed a catalyst concentration gradient and porosity gradient. Anode electrodes are characterized morphologically and electrochemically and the performance of individual cells containing such G-CL designs is measured. The results indicate that incorporation of the appropriate amount of COF materials enables the outer CL not only to have a larger electrochemical surface area (ECSA) and expose more catalytic active sites but also holds a strong proton transfer ability to improve the methanol oxidation reaction (MOR) performance. Due to the presence of the inner layer of the CL formed the methanol gradient oxidation process. With the same platinum-ruthenium (Pt–Ru) catalyst loading, the 5 wt.% COF G-CL anode structure exhibited lower methanol crossover and higher power density (nearly 11% increment) compared with that of the S-CL anode with high methanol concentration (8 M) at 60 °C, showing the promising potential in further applications.

Recent Advances in the Development of Nanocatalysts for Direct Methanol Fuel Cells

Direct methanol fuel cells (DMFCs) have attracted much attention due to their potential application as a power source for portable devices. Their simple construction and operation, associated with compact design, high energy density, and relatively high energy-conversion efficiency, give the DMFCs an advantage over other promising energy production technologies in terms of portability. Nowadays, research on DMFCs has received increased attention in both academics and industries. However, many challenges remain before these systems become commercial, including their costs and durability. As a key material with a high-value cost, noble metal catalysts for both the anode and cathode sides face several problems, which hinder the commercialisation of DMFCs. This paper provides a detailed comprehensive review of recent progress in the development of nanocatalysts (NCs) for the anode and cathode reactions of DMFCs, based on Platinum, Platinum-hybrid, and Platinum-free materials. Particular attention is devoted to the systematisation of published experimental results tested in DMFC devices since 2015, with an emphasis on passive DMFC systems. In addition, a dedicated section was created to include modelling/theoretical studies. Some open problems and remaining challenges are also highlighted in the final section.

Effect of a direct current electric field on CO 2 bubble evolution in a direct methanol fuel cell

In direct methanol fuel cell (DMFC) anode microchannels, the retention of CO2 leads to an anodic polarization reaction. Controlling CO2 discharge in the anode channel by a direct current (DC) electric field is beneficial for reducing the anodic polarization reaction. In this work, numerical simulation was the main scientific research method, and the leaky dielectric model was used to characterize the effect of the electric field force. An unsteady theoretical model was established by bidirectionally coupling the electric field and multiphase flow field, which, for this research, indicates the formation of CO2 Taylor bubble flow in a methanol aqueous solution within a DMFC anodic microchannel. Based on this theoretical model, the regulation mechanism of the DC electric field on the dynamic behavior of Taylor bubble formation in DMFC anode microchannels was studied. In the anode channel, the electric field increases the likelihood that the neck of the CO2 bubble will fracture during Taylor bubble formation. The higher electric field intensity increases the formation rate of CO2 bubbles and reduces their size. In addition, the electric field reduces the number of satellite bubbles in the anode channel and promotes the mass transfer rate of the methanol aqueous solution. The results show that the movement characteristics of CO2 can be effectively controlled by applying a DC electric field in the DMFC anode microchannel, which provides a new way to reduce the anodic polarization effect of the DMFC.

Two-Step Dry Synthesis of Binderless 3D Low Pt-Loading Electrocatalysts for Direct Alkaline Methanol Fuel Cell Anodes

Three-dimensional (3D) porous electrocatalysts of low platinum loading were synthesized by gas-phase pulsed laser ablation (PLA) and deposited on multiwalled carbon nanotubes (MWCNTs) directly grown on a stainless steel mesh current collector by catalyst-free chemical vapor deposition (Pt/MWCNT/SS). The performance of the developed electrocatalysts was evaluated for the methanol oxidation reaction (MOR). The PLA chamber pressure and ablation time were optimized to achieve the highest methanol oxidation current per Pt loading and electrochemically active surface area while maintaining structural stability. The most robust electrocatalyst, obtained with PLA at 10–5 Torr for 5 min, exhibited a 50% higher methanol oxidation current compared to the commercial Pt/C with similar Pt loading. In addition, it showed the lowest loss of active sites after stability tests while maintaining its structural integrity. Increasing the electrolyte temperature from 0 to 80 °C significantly improved the methanol oxidation current on Pt/MWCNT/SS by 13 times compared to 5.8 times for Pt/C. Electrochemical impedance spectroscopy confirmed the faster kinetics of MOR and accelerated oxidation of adsorbed CO on the surface of the Pt/MWCNT/SS relative to the Pt/C.

A novel gas diffusion layer and its application to direct methanol fuel cells

The gas diffusion layer (GDL) is an important component of the membrane electrode assembly of fuel cells (FCs). Its roles include supporting the catalyst layer, collecting current, and transferring and redistributing materials. A conventional GDL consists of a backing layer, typically of commercial carbon paper or carbon cloth, but it suffers from its high cost, narrow pore-size distribution, lack of flexibility and poor conductivity, and a micro-porous layer (MPL) is necessary for better gas/liquid management. A novel flexible gas diffusion layer (GDL) was prepared by vacuum filtration of a suspension of carbon fibers (CFs) and highly-dispersed multi-wall carbon nanotubes (MWCNTs) in a polytetrafluoroethylene (PTFE) binder and water repellent. SEM observations, gas permeability and porosity tests indicate that there is a gradient in the concentration of highly-conductive MWCNTs in the CNT-CF GDL network that facilitates electron transport. A multi-level pore structure is formed, which is beneficial to mass transport. The PTFE is distributed uniformly, which is favorable for the discharge of condensed water from the FCs. When the GDL/CNT-CF is used in the cathode, or in both the cathode and anode in direct methanol FCs, the maximum power densities of single cells are increased by 20% and 35%, respectively, compared with those using a commercial GDL consisting of carbon paper with a MPL due to its excellent mass transfer performance.

Rh-Decorated Three-Dimensional Graphene Aerogel Networks as Highly-Efficient Electrocatalysts for Direct Methanol Fuel Cells

The exploration and development of highly-efficient Pt-alternative catalysts with acceptable costs are very essential for the large-scale commercial applications of direct methanol fuel cell (DMFC) technology. Herein, we demonstrate a facile and cost-effective self-assembly approach to the bottom-up fabrication of Rh-decorated three-dimensional graphene aerogel (Rh/3D-GA) networks as efficient DMFC anode catalysts. With the distinct textural features including large surface area, 3D porous structure, uniform Rh dispersion, and good electron conductivity, the resultant Rh/3D-GA hybrid architecture shows superior electrocatalytic properties toward methanol oxidation reaction, such as large electrochemically active surface area, low onset potential, high mass activity as well as excellent long-term stability, all of which are more competitive than those of Rh catalysts deposited on conventional carbon black, carbon nanotubes, and two-dimensional graphene supports.

Synthesis of TiO2 Composited Nitrogen-doped Carbon Supports for High-Performance Methanol Oxidation Activity

Carbon supports for dispersed platinum (Pt) electrocatalysts in direct methanol fuel cells (DMFCs) are being continuously developed to improve electrochemical performance and catalyst stability. However, carbon supports still require solutions to reduce costs and improve catalyst efficiency. In this study, we prepare well-dispersed Pt electrocatalysts by introducing titanium dioxide (TiO2) into biomass based nitrogen-doped carbon supports. In order to obtain optimized electrochemical performance, different amounts of TiO2 component are controlled by three types (Pt/TNC-2 wt%, Pt/TNC-4 wt%, and Pt/TNC-6 wt%). Especially, the anodic current density of Pt/TNC-4 wt% is 707.0 mA g−1 pt, which is about 1.65 times higher than that of commercial Pt/C (429.1 mA g−1 pt); Pt/TNC-4wt% also exhibits excellent catalytic stability, with a retention rate of 91 %. This novel support provides electrochemical performance improvement including several advantages of improved anodic current density and catalyst stability due to the well-dispersed Pt nanoparticles on the support by the introduction of TiO2 component and nitrogen doping in carbon. Therefore, Pt/TNC-4 wt% may be electrocatalyst a promising catalyst as an anode for high-performance DMFCs.

Ultra-Range Bimetallic Pt–Pd Nanospheres Deposited on Reduced Graphene Sheet as Efficient Electrocatalyst Towards Electrooxidation of Methanol

Direct methanol fuel cells (DMFCs) offers promising possibilities in meeting future energy needs in a most sustainable way. To electro oxidize methanol at anode of DMFCs, till date Pt and Pt-based materials were widely employed. To improve the utilization of precious metals it is highly desirable to disperse them on conductive carbon structures. Here, we synthesized ultra-range bimetallic platinum–palladium (Pt–Pd) nanospheres (NSs) with uniform dispersion on reduced graphene oxide (RGO) sheets by a simple hydrothermal method and studied their efficacies towards methanol oxidation reaction (MOR). From HR-TEM analysis, it was found that the synthesized bimetallic Pt–Pd NSs possess an average particles size of about 5 to 7 nm consistent with XRD data. The MOR electro catalytic activity of bimetallic PtPd-RGO NSs was higher compared to homemade mono metallic Pt-RGO, Pd-RGO catalysts and commercial E-tekPt/C.

Two‐Phase Flow Modeling of Direct Methanol Fuel Cell Anode Compartment

AbstractA quasi two‐dimensional numerical model was developed to predict the two‐phase flow behavior within the anode compartment of direct methanol fuel cells (DMFCs). Different void fraction correlations were employed to examine and estimate the pressure drop, flowrate and methanol concentration variations across the fuel channels. By comparing the modeling results with experimental data, it was discovered that the calculated pressure drop values were highly dependent on the type of void fraction correlation utilized. The best experimental agreement was achieved when using the “separated” flow modeling approach with a void fraction correlation that accounted for surface tension and capillary effects. The “homogenous” flow modeling methodology on the other hand, was found to be inadequate and in all cases, underestimated the two‐phase pressure drop. The model demonstrated that the acceleration and gravitational pressure losses had the lowest and highest impact on the overall two‐phase pressure drop, respectively. The frictional pressure loss effects only started to appear at higher fuel flowrates and at elevated operating current densities. It was also revealed that increasing the cell's operating current density while maintaining the fuel flowrate, would significantly increase the overall two‐phase pressure drop with negligible impact on the net methanol concentration across the anode compartment.

Perforation Optimization of DMFC Anode Porous Medium

Carbon Dioxide management is essential to the development of Direct Methanol Fuel Cell Anode. CO2 bubbles evolution at the anode can create large mass transport loss and block the sites where the triple phase boundary occurs for the electrochemical reaction. The gas can be trapped in the Gas diffusion layer (GDL) and block the channels from the incoming fuel [1-2]. Researchers have studied the mechanism and the dynamics by visualizations of how CO2 bubbles evolve from the catalyst layers [3-5]. Some studies have been done to the anode structure to improve the performances by modifying the material, wettability, porosity and thickness [6-8]. However, disagreements have been confirmed from different design aspects to whether those modifications reduce the mass transport loss or not [9-11]. In this study, pathways/perforations were created by laser perforating the Gas Diffusion layer (GDL) to enhance the mass transport from and to the catalyst layer. Results have shown superiority of the perforated GDL over the conventional GDL. Further optimization of the perforation diameter, the spacing along the lateral and channel directions have been accomplished. First, the perforation diameter size was investigated with minimum number of holes, 16 holes, spaced with 2 millimeters in lateral and channel directions over the 1 cm^2 active area of the electrode, as can be seen in Figure 1A. The 60-micron diameter showed little improvement over the virgin GDL while further increase of the diameter caused massive mass transport loss. Secondly, further optimization of the spacing in the lateral and channel directions in Figure 1B, it was found that the 60-micron diameter with 1 millimeter in lateral spacing and 2 millimeter in channel spacing increased the maximum power density by roughly 30% compared to virgin GDL. Figure1: A) Different perforation diameter ranging from 60-500 micron with 16 holes; B) Spacing optimization in lateral and channel directions. Figure 1

Towards a High-Performance DMFC Membrane Electrode Assembly Using Iron-Doped Metal Organic Framework Catalysts on the Cathode

Direct methanol fuel cells (DMFC) have several advantages for a broad spectrum of energy density demanding applications, ranging from portable devices to stationary backup power. DMFCs deliver power at high efficiencies compared to internal combustion technologies and use high energy density methanol as the fuel. However, DMFCs face several challenges, including methanol crossover at the cathode and slow methanol oxidation reaction (MOR) kinetics at anode that impede its performance. Hence, high loadings of a platinum group metal (PGM) catalyst are normally needed on both the anode and cathode, leading to high raw material catalyst costs. In this work, a PGM-free iron catalyst derived from metal organic framework precursors (Fe-MOF) is used on the cathode side to catalyze the oxygen reduction reaction (ORR). The PGM-free cathode has shown a high tolerance to methanol crossover relative to standard PGM catalysts and high performance relative to previously reported DMFC PGM-free cathode performances in the field. A wide range of operating conditions were tested, and we evaluated the maximum power density using pure oxygen and air with varying methanol concentration. We conducted our tests with a custom, integrated H2 reference electrode that separately provided the anode and cathode overpotentials. This is necessary for cell and electrode optimization since DMFC anode overpotentials are large relative to that of H2 PEMFCs and cannot be used as a quasi-reference electrode. Furthermore, we performed long term durability tests to evaluate PGM-free catalyst stability in the DMFC environment. This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Fuel Cell Technologies Office (FCTO) under Award Number DE-EE0008440.

Carbon-Supported Pt and Pt–Ir Nanowires for Methanol Electro-Oxidation in Acidic Media

Direct methanol fuel cells are promising electrochemical energy conversion devices. But, more efficient and stable and less expensive catalysts are still required. Here, we successfully synthesized Pt/C and Pt0.5–Ir0.5/C, Pt0.6–Ir0.4/C, Pt0.7–Ir0.3/C, and Pt0.8–Ir0.2/C nanowires by the chemical reduction of the metallic precursors by formic acid and tested them towards methanol electro-oxidation in acidic media. Neither surfactants nor templates were used during the syntheses. The nanowires catalysts were compared with a commercial state-of-art catalyst aiming the observation of the properties improvements derived from both alloying Pt with Ir and morphology change from nanoparticles to nanowires. Well-defined and slightly agglomerated over the carbon nanowires (diameters and lengths of approximately 5 and 20 nm, respectively) were obtained, the fact that is ascribed to the 40 wt% metal loading. In addition, accelerated degradation tests showed that Pt0.6–Ir0.4/C, Pt0.7–Ir0.3/C and Pt0.8–Ir0.2/C catalysts are more stable than commercial Pt/C. All synthesized nanowires catalysts were more active towards methanol electro-oxidation than the commercial Pt/C. The Pt0.5–Ir0.5/C sample shows Pt mass activities 7 times that of commercial Pt/C. However, the Pt0.8–Ir0.2/C catalyst presented the best specific activity (6 times that of commercial Pt/C), have the highest currents in the derivative voltammetry and the oxidation potential shifts negatively 100 mV in comparison with the commercial Pt/C catalyst. Hence, the nanowires developed in this study are indicated as potential promising catalysts and can be applied successfully as direct methanol fuel cell anodes.

Pt Nanoparticle-Loaded Graphene Aerogel Microspheres with Excellent Methanol Electro-Oxidation Performance.

Platinum-decorated graphene aerogel microspheres were fabricated through a combined electrospraying, freeze-casting, and solvothermal process. Platinum nanoparticles with a narrow size distribution are evenly anchored on the graphene aerogel microspheres without agglomeration benefitting from the distinct center-diverging microchannel structure of the graphene aerogel microspheres, which results in the as-prepared catalysts presenting excellent electrocatalytic performance including high electrocatalytic activity and high poison tolerance toward methanol electro-oxidation, showing great potential for direct methanol fuel cell anode catalysts. In particular, the platinum-decorated graphene aerogel microspheres exhibit an extremely high mass activity of 1098.9 mA mg-1 toward methanol oxidation as well as excellent antipoisoning ability, which are dramatically enhanced compared with Pt particles dispersed on graphene oxide and commercial carbon black supports.

Vapor-feed low temperature direct methanol fuel cell with Pt and PtRu electrodes: Chemistry insight

The performance of a vapor-fed low-temperature direct methanol fuel cell (DMFC) with Nafion proton exchange membrane has been analyzed and compared to identical fuel cell assembly supplied with liquid methanol diluted in water. The cell was subjected to a wide range of methanol concentrations and power loads. The potentiostatic measurements were correlated with the composition of gases released at the anode determined by on-line mass spectroscopy. Both Pt and PtRu catalysts supported on carbon were used at the DMFC anode while cathode comprised pristine Pt on C in all cases. It is demonstrated experimentally that although the vapor-fed system is generally more complex and require an additional source of heat or utilization of the waste reaction heat, it shows its potential to be more efficient and tunable than conventional liquid-fed FCs as well as more resistant to poisoning, even in the absence of ruthenium in the anode catalyst. Energy efficiency of 30% and power density exceeding 70 mW cm−2 were achieved with Pt/C electrodes without any noticeable long-term degradation.

Two-dimensional PtRu Nanoclusters Carbon Based Electrocatalysts for Methanol Oxidation

A novel method to prepare an electrocatalyst with a new structure and high catalytic performance was reported. Two-dimensional (2D) PtRu nanoclusters have been successfully deposited on graphene oxide and carbon black supports. Compared with the commercial 3D E-TEK PtRu samples, the prepared 2D PtRu composites have larger electrochemically active surface area and display much higher catalytic activity toward methanol oxidation reaction. The preparation method mainly includes the following procedures: oxidation of carbon matrix, Pb2+ adsorption on the surface of carbon support, Pb2+ electrochemical reduction and galvanic displacement of Pb0 by Pt2+ and Ru3+. The method developed in this study could be viable for solving the problem of low electrocatalytic activity in direct methanol fuel cell anodes.

Maximized specific activity for the methanol electrooxidation by the optimized PtRu-TiO2-carbon nano-composite structure

The kinetics of the methanol electrooxidation needs to be improved to increase the power density using a lower amount of noble metal catalysts (i.e., Pt and Ru) in direct methanol fuel cells (DMFC). PtRu nanoparticles (∼5 nm) supported on TiO2-nanoparticle (∼4 nm)-coated carbon nanofibers were proposed as an alternative active catalyst for the DMFC. The nano-sized TiO2 can provide a short distance of electron transport from PtRu (reaction site) to the carbon (current collector). At the composite catalyst, the activity enhancement by the PtRu-TiO2 interaction suggested the sufficient electron conductivity at the electrode. The maximized specific activity of the proposed catalyst was 3 times higher compared to that of the commercial PtRu/C. The pore structure of the catalyst was changed by the oxidation conditions due to gasification of the carbon, and the higher activity was obtained by the catalyst with the higher surface area of the micropores (>800 m2 g−1). However, the contribution of micropore would be a secondary effect to the activity. The maximized specific activity was obtained when the volumes of PtRu and TiO2 were similar for the almost same size (around 5 nm) of these particles suggesting that the number of contact points between the PtRu and TiO2 were optimized and the interaction between them was maximized. The PtRu-TiO2-carbon nano-composite catalyst has a high potential as an alternative catalyst as the anode of DMFC.

A novel method for analysis and prediction of methanol mass transfer in direct methanol fuel cell

Two-phase gas/liquid flows coupled with electrochemical reactions in the anode of direct methanol fuel cell (DMFC) are quite complicated transport phenomena. The methanol transport is a key factor influencing the performance as well as fuel utilization efficiency. In this paper, a dimensionless correlation of methanol mass transfer in DMFC anode is proposed. Firstly, a method for detecting methanol concentration in catalyst layer was developed, which is the key parameter to obtain the mass transfer coefficient. Then, the influences of the various factors on the mass transfer coefficient, including physical properties of fluid, structures of the electrode, cell configuration and cell operation conditions, were investigated. And a correlation between four dimensionless groups, i.e., Sh, Re, Sc and Π (ratio of consumption and feeding rate of methanol), was deduced using the dimensional analysis. Finally, MEA optimization and fuel utilization efficiency evaluation based on the above analysis is performed. A maximum power density of 178 mW cm−2 at 80 °C and atomistic air is achieved, 40% higher than that of commercial one made by Johnson Matthery.